First, make sure you set a reference to "Microsoft Scripting Runtime"
(Under Tools|References)

But there's nothing in your posted code that uses FSO.

Second, Chip Pearson explains why it's not good to use:

Dim Something As New SomeObject
he
http://www.cpearson.com/excel/DeclaringVariables.aspx
look for
Don't Use Auto-Instancing Object Variables








Bobby wrote:

Hi ,
I am trying to compile the following code.But iam getting the following error:
Error
*****
User Defined Type not define :
Public fso As New Scripting.FileSystemObject
*****
Code
*****
Option Explicit

Public fso As New Scripting.FileSystemObject

Public vertView As Boolean

Public Sub Auto_Open()
On Error GoTo ErrorHandler

Dim newMenu As Menu, menuName As String


menuName = Application.MenuBars(xlWorksheet).Menus("MainMenu" ).Caption

Exit Sub
ErrorHandler:
If Err.Number = 1004 Then
Set newMenu =
Application.MenuBars(xlWorksheet).Menus.Add("&Main Menu", _
Application.MenuBars(xlWorksheet).Menus.Count)

newMenu.MenuItems.Add "E&xport Data File ...", "ExportToFile"
End If
End Sub

--

Dave Peterson